The present invention relates to a cooling arrangement for a die-casting metal mold, and more particularly, to such a cooling arrangement capable of uniformly cooling the entirety of the die-casting metal mold.
A conventional cooling arrangement for a die-casting metal mold is described in Laid-open Japanese Patent application Publication No. Sho-58-211405. In the disclosed arrangement, a coolant passage is penetratingly formed in the metal mold. The passage has one open end connected to a coolant accumulation tank through a coolant inlet pipe, and has another open end connected to the tank through a coolant outlet pipe. A pump is provided at the coolant outlet pipe. Upon actuation of the pump, the coolant in the tank is introduced into the coolant passage in the metal mold through the coolant inlet pipe, and is then circulated to the tank through the coolant outlet pipe. A temperature of the coolant in the tank is controlled by a tank temperature controller for supplying the coolant at its optimum temperature to the die-casting metal mold.
Laid-open Japanese Patent Application Publication No. Hei-6-71408 discloses a method for forming a coolant passage in a die-casting metal mold. According to the disclosed method, a continuous deep groove is formed by a cut machining at a surface opposite to a mold cavity, and a lid is covered over the formed groove to provide a coolant passage. This method is designed to overcome the deficiency in a conventional drilling where a desirable configuration and orientation of the passage cannot be provided.
Further, still another conventional cooling arrangement is shown in FIG. 7 in which a linear cooing bore 130 is bored from a surface opposite to a mold cavity 125 to a position adjacent to the mold cavity 125, and a coolant supply pipe 105 extends through and generally concentrically with the cooling bore 130. A coolant is supplied through the coolant supply pipe 105 in a direction indicated by an arrow in FIG. 7. The supplied coolant passes through a space defined between an inner peripheral surface of the cooling bore 130 and an outer peripheral surface of the coolant supply pipe 105, and is then discharged through a coolant discharge pipe 107. Thus, the metal mold can be locally cooled by a linear coolant passage extending in a depthwise direction (thickness direction) of the metal mold.
However, in these conventional cooling arrangements, water is generally employed as the coolant. In such a case, clogging of the coolant passage may occur due to deposition of fur on the coolant passage or cooling efficiency may be excessively lowered due to boiling of the water, if the coolant passage is located adjacent to the mold cavity. In view of this reason, the coolant passage must be positioned away from the mold cavity by a predetermined distance.
Further, if a cross-sectional area of the coolant passage is insufficiently small, it would be impossible to cool a wide range of the mold cavity simultaneously, and therefore, it would be difficult to uniformly cool the entirety of the mold cavity.
Furthermore, in a conventional cooling arrangement, only one coolant passage is formed in the mold cavity. In this connection, a coolant adjacent to the coolant inlet has a low temperature, whereas a coolant adjacent to the coolant outlet has a high temperature, which cannot uniformly cool the entirety of the mold cavity at an even temperature. Moreover, a region of the mold cavity and ambient region thereof cannot be uniformly cooled with the only one coolant passage. That is, it would be difficult to uniformly distribute the passage along the mold cavity due to a three dimensional construction of the mold cavity.
Therefore, it is an object of the present invention to provide a cooling arrangement capable of uniformly cooling an entire region of the die-casting metal mold.
In order to attain the object, the present invention provides a cooling arrangement 1 for cooling a die-casting metal mold 2 having a stationary die 24 and a movable die 22 defining a mold cavity 25 in combination with the stationary die 24, the cooling arrangement including coolant passage means formed in an interior of the die-casting metal mold 2 for allowing a coolant to pass therethrough for cooling the die-casting metal mold 2, the improvement wherein the coolant is made from an oil, and the coolant passage means comprises a plurality of coolant passages A,B,C,D,E,F,G formed at least in the movable die 22, and each of the coolant passages A,B,C,D,E,F,G is defined by a deep and wide groove 30,32,34,36,38 and a partitioning plate 31,33,35,37,39 disposed in the groove 30,32,34,36,38, each groove 30,32,34, 36,38 and each partitioning plate 31,33,35,37,39 having shapes in conformance with a shape of the mold cavity 25 and being positioned adjacent thereto, and a temperature controller 9,10 with a cooling device 11,12 is connected to each coolant passage A,B,C,D,E,F,G, and the plurality of coolant passages A,B,C,D,E are grouped into a plurality of groups (A,B,C,D) and (E,F,G), and necessary numbers of the temperature controllers 9,10 are provided in accordance with the numbers of the groups to provide, for each group, a coolant circulation circuit 3,4 including a coolant supply circuit 5,6 and a coolant discharge circuit 7,8 with the associated temperature controller 9,10, whereby cooling control is performed independent of each group (A,B,C,D) and (E,F,G).
With the cooling arrangement for cooling the die-casting metal mold, clogging of the coolant passage with the fur can be prevented, and excessive lowering of the cooling performance due to boiling of the coolant can be avoided, since oil is used as the coolant. Further, an entire die-casting product can be uniformly cooled, since the coolant passage can be positioned close to the mold cavity and since the mold cavity surface can be uniformly cooled by supplying the coolant in an extensive region. As a result, shot cycle can be remarkably shortened. Further, difference in a temperature at or around the coolant supply circuit and a temperature at or around the coolant discharge circuit can be severely taken into consideration for attaining more uniform cooling to the mold product because of the formation of the plurality of coolant passages.
Further, the plurality of the coolant passages are grouped into a plurality of groups, and the temperature controllers are provided in correspondence to the groups, and the coolant circulation circuit constituted by the coolant supply circuit and the coolant discharge circuit is provided in association with the temperature controller for controlling cooling independent of each group. Therefore, a desired portion of the metal mold can be cooled, and control to the temperature of the coolant and control to the supply of the coolant can be performed independently of each group. Consequently, more precise cooling control can be achieved.
In another aspect of the invention, there is provided a cooling arrangement 1 for cooling a die-casting metal mold 2 having a stationary die 24 and a movable die 22 defining a mold cavity 25 in combination with the stationary die 24, the cooling arrangement including coolant passage means formed in an interior of the die-casting metal mold 2 for allowing a coolant to pass therethrough for cooling the die-casing metal mold 2, the improvement wherein the coolant is made from an oil, and the coolant passage means comprises a plurality of coolant passages A,B,C,D,E,F,G formed at least in the movable die 22, and each of the coolant passages A,B,C,D,E,F,G is defined by a deep and wide groove 30,32,34,36,38 and a partitioning plate 31,33,35,37,39 disposed in the groove 30,32,34,36,38, each groove 30,32,34, 36,38 and each partitioning plate 31,33,35,37,39 having shapes in conformance with a shape of the mold cavity 25 and being positioned adjacent thereto, the partitioning plate 31,33,3537,39 having an outer surface formed with at least one auxiliary path 31e,31f,31g,33e,33f at a position adjacent to the mold cavity 25 to provide a branch flow of the coolant in each coolant passage A,B,C,D,E,F,G, and a temperature controller 9,10 with a cooling device 11,12 is connected to each coolant passage A,B,C,D,E,F,G.
With the cooling arrangement for cooling the die-casting metal mold, clogging of the coolant passage with the fur can be prevented, and excessive lowering of the cooling performance due to boiling of the coolant can be avoided, since oil is used as the coolant. Further, an entire die-casting product can be uniformly cooled, since the coolant passage can be positioned close to the mold cavity and since the mold cavity surface can be uniformly cooled by supplying the coolant in an extensive region. As a result, shot cycle can be remarkably shortened. Further, difference in a temperature at or around the coolant supply circuit and a temperature at or around the coolant discharge circuit can be severely taken into consideration for attaining more uniform cooling to the mold product because of the formation of the plurality of coolant passages.
Further, the cooling oil can be distributed to wider area by the formation of the auxiliary path to further promote uniform cooling. The auxiliary path can be easily provided by forming a groove at the outer surface of the partitioning plate.